1. Technical Field
The present invention relates to ferroelectric capacitors and semiconductor devices.
2. Related Art
A ferroelectric memory device (FeRAM) is a nonvolatile memory that is capable of low voltage and high speed operations, and its memory cell can be composed of one transistor and one capacitor (1T/1C), such that an integration to the level of DRAM is possible. Accordingly, ferroelectric memory devices are highly expected as large capacity nonvolatile memories. In order to have a ferroelectric capacitor composing a ferroelectric memory device exhibit its ferroelectric characteristics to its maximum, the crystal orientation of each of the layers composing the ferroelectric capacitor is very important. An example of related art is described in Japanese laid-open patent application JP-A-2000-40799.
In a ferroelectric capacitor composed of a ferroelectric layer formed by a metal organic chemical vapor deposition (MOCVD) method and upper and lower electrodes interposing the ferroelectric layer and formed by a sputter method, adhesion at an interface between the ferroelectric layer and the upper electrode may be poor. Also, an upper layer of the ferroelectric layer may be damaged as a result of the sputtering, and its nonconductive property may be damaged. This is one of the causes that generate a leakage current in the ferroelectric capacitor.